# Copyright 2015 The Bazel Authors. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#  http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""This package contains various functions used when building containers."""


def ExtractValue(value):
  """Return the contents of a file point to by value if it starts with an @.

  Args:
    value: The possible filename to extract or a string.

  Returns:
    The content of the file if value starts with an @, or the passed value.
  """
  if value.startswith('@'):
    with open(value[1:], 'r') as f:
      value = f.read()
  return value
